This invention relates to the aligning of glass sheets in a bending process wherein horizontally disposed glass sheets are conveyed through a heating furnace and then brought into a bending apparatus where they must be brought into accurate alignment with the shaping means. More particularly, this invention provides positive orientation of glass sheets in the longitudinal and lateral directions as well as angularly within the bending station itself and assures that such orientation is maintained until the glass sheets are engaged by the shaping means. The problem of aligning glass sheets is particularly acute when the glass sheets are conveyed on a gas support system and, therefore, another of the objects of the present invention is to provide improved alignment means for such a gas support system. Another problem dealt with by the invention is the aligning of a plurality of glass sheets side-by-side preparatory to being bent simultaneously. The invention is particularly pertinent to the production of bent automotive glazing.
Many arrangements for aligning glass sheets in bending apparatuses are known in the prior art. Perhaps the simplest arrangement is to cause conveyor rolls carrying the glass sheet to stop when the glass has progressed to a predetermined location within the bending apparatus. Other relatively simple means to locate glass sheets include peg-like stop means against which the glass sheets abut, such as in U.S. Pat. No. 3,573,889 to McMaster et al. and U.S. Pat. No. 3,676,098 to Hall. In U.S. Pat. No. 3,425,818 to Plumat, wires serve as lateral guides for glass sheets. In each of these above-described prior art arrangements there is no provision for correcting a misorientation of a glass sheet. Also, the force of a glass sheet striking a peg shaped stop can distort the adjacent marginal portions of the glass sheet or cause other damage to the glass sheet.
U.S. Pat. No. 3,600,150 to Rougeux discloses a complex aligning apparatus wherein reciprocated bars are advanced into abutment with all four sides of a rectangular sheet of glass. Such a large number of moving parts is preferably avoided. The reference arrangement also appears to entail a time delay in the bending process. Moreover, the aligning bars apparently must be withdrawn from the bending area before bending is initiated, and thereby fails to positively maintain the alignment until bending begins.
A number of patents disclose means for conveying irregularly-shaped glass sheets in fixed orientations through a heating furnace. These include U.S. Pat. No. 3,485,616 (Nitschke), U.S. Pat. No. 3,594,149 (Pickavance et al.), and U.S. Pat. No. 3,827,547 (Nixon). None of these patents, however, deal with the problem of bringing glass sheets into proper alignment in a bending apparatus, but are limited to conveying glass sheets through a furnace. Moreover, it is preferable that conveying means separate from the furnace conveying means be provided for carrying the glass sheets out of the furnace and into the bending apparatus so that the glass sheets may pass through the furnace at a relatively slow rate and then be brought into the bending apparatus at a relatively rapid rate.
Means for bringing glass sheets into proper alignment near the exit end of a furnace are shown in U.S. Pat. Nos. 3,701,643 and 3,992,182, both to R. G. Frank. After the glass sheets are aligned, however, they are released by the aligning means and conveyed into the bending apparatus, during which time they may become misaligned again. Similar arrangements, but in which the glass sheets are held in alignment until deposited in the bending station, are shown in U.S. Pat. No. 3,713,799 to McMaster and U.S. Pat. No. 3,846,104 to Seymour. The aligning devices in all four of these patents, but in particular the latter two, are very complex machines with many moving parts and would appear to require considerable reconstruction for each product change. Additionally, such arrangements do not appear to be adaptable to handling a plurality of sheets side by side without greatly increasing the complexity of the machinery further.
Accordingly, there has been a need for bringing glass sheets of any shape into an accurately predetermined position within a bending apparatus and to positively retain the glass sheet in that position until the bending means engage the glass sheet. It would be even more desirable if these requirements could be met while processing a plurality of glass sheets side-by-side and/or while the glass sheets are supported on a layer of gases.